Transparency Block Configurations

LU1

For LU1 sessions, three transparency-block formats containing ASCII data are supported.

The first is the standard IBM transparency block. In an LU1 session, each transparency block must be preceded by a 2-byte header containing either hexadecimal code 0x35 or 0x36, and a character count.

0x35 indicates that the data block is in EBCDIC, the native IBM host character set. The block is translated to ASCII before sending it to the printer.

0x36 is an extension to the LU1 SCS control set, which indicates that a block contains ASCII data.

A second format, configured in the LU1 page of Printer settings, allows you to indicate that transparency blocks beginning with 0x35 contain ASCII data rather than EBCDIC. If selected, this option will apply to all transparency blocks in all print jobs run by the session. The third format, also defined by IBM, created an extension to its SCS controls that has a three-byte header. In Raw Mode, the data block is sent directly to the print device. In GDI Mode, the data block is broken down and interpreted through the Windows Graphics Device Interface. In GDI mode, all formatting within transparency blocks must be done with PCL printer commands.

LU3 and LU4

SCS transparency is not defined by IBM for LU4 sessions, and LU3 does not support SCS. PCL commands may be embedded directly into the text stream to perform formatting in LU3 and LU4. You can also put PCL commands in the text stream in LU1 as well.

To configure [0x35] transparency blocks